Heretofore, pneumatic tires each having a tread pattern which is asymmetric between outer and inner sides of a vehicle with respect to the vicinity of the tire equator when it is attached to a vehicle have been proposed. Generally, in a pneumatic tire having such an asymmetric tread pattern, on its tread surface, an outer side region of a vehicle, to be placed on the outer side of the vehicle, is provided with a pattern in which importance is placed on handling stability, and an inner side region of the vehicle, to be placed on the inner side of the vehicle, is provided with a pattern in which importance is placed on drainage performance.
As a specific form of such an asymmetric tread pattern, a pneumatic tire has been disclosed which includes circumferential grooves having different groove widths between the outer side region and the inner side region of a vehicle (e.g., see Japanese Unexamined Patent Application Laid-open Publication No. 2004-90763 (hereinafter referred to as Patent Document 1)). This asymmetric tread pattern can favorably improve drainage performance on a wet road surface, particularly hydroplaning resistance, and tire noise reduction.
Although the asymmetric tread pattern disclosed in Patent Document 1 can favorably improve drainage performance on a wet road surface, the asymmetric tread pattern cannot go as far as to effectively improve handling stability or wear resistance, which is in a trade-off relationship with the drainage performance.
In view of the above-described problem, an object of the present invention is to provide a pneumatic tire having an asymmetric tread pattern, having improved handling stability on a dry road surface and improved drainage performance on a wet road surface, and also having improved ride quality, improved low-noise performance, and improved wear resistance.